Making sense of good taste

Professor Peter Barham turned up to address a small group at the Delaire Graff Estate wearing a maroon waistcoat with hand-painted penguins on either side. A specialist in polymer physics who expresses his love for these birds through his wardrobe (“Waistcoats when it’s something more upmarket,” he confided later), Barham is better known by some for his collaboration with chef Heston Blumenthal in exploring molecular astronomy cooking techniques.

Before meeting Blumenthal, Barham had opened a copy of Cordon Bleu Cookery to fill the hours left empty by a completed PhD.
A new hobby of baking birthday cakes for colleagues at Bristol University — or, more precisely, a flopped Black Forest gateau — led him to addressing cookery myths. “I was so cross with that book,” said Barham. “I read it like a scientific text, expecting if I ­followed every instruction I would get exactly the same result as the photograph.”

He reworked the recipe for a spoof lecture at the university, explaining in pure physics terms (while de-

monstrating the process) how to bake a perfect Black Forest gateau every time. It was subsequently published in his book The Science of Cooking (Springer, 2001). The lecture went public and culminated in presentations to the United Kingdom’s Women’s Institute and an invitation to the international workshop on molecular and physical gastronomy organised by Oxford physicist Nicholas Kurti.

Blumenthal was following a similar path, questioning culinary “rules”. He contacted Barham, who became the first academic in Blumenthal’s consulting network. Barham is now an honorary professor in the field at the University of Copenhagen, where he is researching and teaching and has completed a major review of the subject.

In its simplest terms, Barham and his co-authors define molecular

gastronomy as “the scientific study of why some food tastes terrible, some is mediocre, some good and, occasionally, some absolutely delicious”. Chemistry lies at the heart of this emerging discipline and Barham’s conclusions on our perception of flavour is interesting: “Flavour is a concept we individually construct in our brains using every sensory input.”

In a video clip, Barham, sporting another a penguin-pattern waistcoat, and a young Blumenthal fry steaks and prove that browning meat does not seal juices in but forces water out.

He advises a test for gauging how well done a steak is that is more accurate than prodding: weigh it before and after cooking. If it has lost 5% of its original weight, it will be rare; if it has lost 10%, it will be medium rare. Anything more than that and he believes it is not worth eating.

Speaking about taste, Barham’s statements got more extreme: “MSG is an essential food we must eat regularly or we are going to die.” Umami, our fifth taste, besides sweet, salty, sour and bitter, is that intense savouriness, almost imperceptible crystals found in soy sauce and Parmesan cheese.

Barham explained why humans found it so “moreish”: “It’s the sodium salt of glutamic acid, also known as monosodium glutamate or MSG.” As with salt, we were “designed” to like it because of insufficient quantities in our natural diet.

MSG is also in the tomato — which led to an aside that might change the way you approach Caprese salad: a whole tomato has no flavour. “If you very carefully extract the liquid of a tomato with a syringe,” Barham said, “it will taste of nothing.”

By processing it — biting , cutting or cooking — an enzyme in the liquid breaks down larger molecules in the solid parts to form smaller molecules that give the fruit its flavour. The enzyme is permanently damaged below 2˚C or 3˚C and reacts differently when cut crossways, so tomatoes taste better sliced and stored out of the fridge.

The biology of taste
Barham described the widely accepted diagram of taste receptors on the tongue (sour on the sides, bitter at the back, sweet upfront) as “nonsense”. He said everyone has a unique distribution of taste receptors — even identical twins have different “taste maps” — and encouraged the audience to map their own tongues at home, using cotton buds dipped in sweet, salty, sour, bitter and umami solutions, to get a better understanding of how we taste food.

We know that taste works through the taste buds in the mouth and aroma in the nose. But, according to Barham, we react to changes in smells, not the concentration, which means we quickly adapt to aromas. It means that constant flavours can become “boring” and are ignored, which Barham said he illustrated by getting audiences to chew mint-flavoured gum. After five minutes, no one could taste the mint.

“I would ask them to drink some sweetened cold water and, suddenly, miraculously, the mint came back. That’s because there was a single molecule — menthone — giving the aroma.

“Now chewing gum manufacturers use multiple molecules cycling between each other. It [the flavour] lasts longer, but I was annoyed because the demos didn’t work any more.”

“So how do we describe flavour?” he asked. “It always comes back to words.” To illustrate it, Barham asked three audience members to sample glasses of red and white wine and share their impressions. The white, a chardonnay, elicited descriptions such as “grapefruit”, whereas the red was likened to “cherries” and “strawberries” — but it was the same wine, coloured red with food dye. Colour could dominate taste and tell us what to expect, he said.

Even what we hear affects us. Chip packets rustle loudly for a reason — crackling cellophane makes stale chips “sound” crisp, leading us to believe they are fresh. In the same way, the sound of lapping waves heightens seafood flavour.

Barham urged the audience to conduct experiments such as listening to a recording of yourself eating crunchy food while eating something soft or tasting plain yoghurt while stroking a silky surface to experience enhanced creaminess — texture is also important.

Individual memory associations and taste-bud patterns mean no two people experience the same sensation or receive the same signal when tasting the same food, which brought us back to the old philosophical chestnut: How do we know that the blackcurrant I taste is the same as the blackcurrant you taste? Are we simply reacting like Pavlovian dogs?

“Yes, you could say that,” Barham said. “We are all victims of our own psychology and it’s frighteningly easy to fool ourselves with food.”

The lecture was presented by the Culinary Equipment Company. Email [email protected] for information about future events